[nitrogen]

It's probably the modem's MAC that matters for cable, and that is probably tied to the account.

[ANTSANTS]

I have a cable internet connection and know the difference between a modem and a router. You'll have to take my word for it that every time I change my router's MAC address, my public IP does as well.

[nitrogen]

Interesting. I've always had to activate a specific modem MAC with my cable provider.